Patent GB-971973-A (GB)
Title: Slip-resistant thermoplastic polymer products
IPC: C08J7/048
Filed: 1961-10-24
Abstract: A thermoplastic polymer product having a slip-resistant surface comprises a thermoplastic polymer having an adherent film, on at least one surface thereof, of a composition comprising particles of an alkali-stabilized colloidal silica and particles of a finely divided copolymer comprising the interpolymerization product of a monovinylidene aromatic hydrocarbon, an alkyl ester of acrylic or methacrylic acid and an ethylenically unsaturated organic carboxylic compound having at least one carboxyl group.  The copolymer may be an interpolymer of from 25 to 65% by weight of styrene, 60 to 34,5% by weight of an alkyl acrylate and from 0,5 to 14% by weight of an ethylenically unsaturated, organic carboxylic compound containing from 3 to 9 carbon atoms, and having at least one carboxyl group. The thermoplastic polymer to which the adherent film is adherent may be in the form of a sheet, film or coating e.g. of polyolefin such as polyethylene, polypropylene, polyvinyl acetate or chloride, or polystyrene, which may be coated on cellulosic sheet such as paper or cardboard.  The alkyl acrylate or methacrylate of the interpolymer may have an alkyl group containing 1-20 carbon atoms e.g. amyl, hexyl, 2-ethyl hexyl, octyl, 2-methyl pentyl, heptyl, 3-methyl heptyl, tridecyl, tetradecyl, acrylate and methacrylate, and that of the oxo alcohol of isobutylene dimer.  The unsaturated compound of the interpolymer may be an alkyl half ester of maleic acid in which the alkyl group contains from 1 to 4 carbon atoms, further examples of suitable compounds being given.  The interpolymer may include an unsaturated nitrile.  The thermoplastic polymer is a polyolefin, and the interpolymer may comprise from 25 to 60% by weight of styrene, 60-35% by weight of an alkyl ester of acrylic acid containing from 5 to 20 carbon atoms in the alkyl group, from 5 to 2% by weight of a copolymerizable ethylenically unsaturated carboxylic compound containing from 3 to 9 carbon atoms and having at least one carboxyl group, and from 10 to 3% by weight of vinyl nitrile or vinylidene nitrile.  The polyolefine may be a polyethylene, the carboxylic compound may be a methacrylic acid, the nitrile acrylonitrile, and the ester an alkyl half ester of maleic acid.  The alkali-stabilized colloidal silica may have a SiO2 to M2O weight ratio of from 10 : 1 to 500 : 1 (M being an alkali metal) and be present in the range of 10 to 500 parts by weight of SiO2 per 100 parts by weight of the interpolymer.  The composition may be applied to a surface of the thermoplastic polymer as an aqueous dispersion and the continuous or discontinuous coating thus obtained subsequently dried.  The invention also comprises a transparent flexible polyethylene sheet having a thickness of at least 0,5 mil and having a slip-resistant surface, the sheet having a continuous adherent p  film on at least one surface thereof, of a composition comprising (i) a uniform mixture of particles of an alkali-stabilized colloidal silica having a SiO2 to Na2O weight ratio of from 10 : 1 to 500 : 1 and an average particle size of 5 to 80 millimicrons, and particles of a finely divided interpolymer of from 30 to 48% by weight of styrene, 69,5 to 38% by weight of octyl acrylate and from 0,5 to 14% by weight of an ethylenically unsaturated organic carboxylic compound containing from 3 to 9 carbon atoms and having at least one carboxyl group, the particles of the interpolymer having a particle size between 150 and 250 Angstroms; the quantity of colloidal silica in the film being in the range of from 10 to 500 parts by weight of SiO2 per 100 parts by weight of the interpolymer; or (ii) a uniform mixture of particles of an alkali-stabilized colloidal silica having a SiO2 to Na2O weight ratio of from 10 : 1 to 500 : 1 and an average particle size of 5 to 80 millimicrons, and particles of a finely divided interpolymer of from 30 to 48% by weight of styrene, 69,5 to 38% by weight of octyl acrylate and from 0,5 to 14% by weight of an ethylenically unsaturated organic carboxylic compound containing from 3 to 9 carbon atoms and having at least one carboxyl group, the particles of the interpolymer having a particle size between 150 Angstroms, the quantity of colloidal silica in the film being in the range of from 10 to 500 parts by weight of SiO2 per 100 parts by weight of the interpolymer.  The monovinylidene aromatic hydrocarbon may be styrene, alpha methyl- and alpha methyl-paramethyl-styrene, parachloro-, parabromo-, and paramethyl-styrene, 2,4- and 2,5-dichlorostyrene, meta-ethylstyrene, para-isopropylstyrene and vinyl naphthalene, or mixtures thereof.  The product may be made up into containers, or containers fabricated from uncoated thermoplastic polymer sheets may have the coating applied thereto by brushing, spraying or the like.